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41.
Because of its significant toxicological effects on the environment and human health,arsenic(As) is a major global issue.In this study,an Fe-based metal-organic framework(MOF)(Materials of Institut Lavoisier:MIL-100(Fe)) which was impregnated with reduced graphene oxide(rGO) by using a simple hydrothermal method and coated with birnessitetype manganese oxide(δ-MnO_2) using the one-pot reaction process(MIL-100(Fe)/rGO/δ-MnO_2 nanocomposites) was synthesized and applied successfully in As removal.The removal efficiency was rapid,the equilibrium was achieved in 40 min and 120 min for As(Ⅲ) and As(Ⅴ),respectively,at a level of 5 mg/L.The maximum adsorption capacities of As(Ⅲ) and As(Ⅴ) at pH 2 were 192.67 mg/g and 162.07 mg/g,respectively.The adsorbent revealed high stability in pH range 2-9 and saturated adsorbent can be fully regenerated at least five runs.The adsorption process can be described by the pseudo-second-order kinetic model and Langmuir monolayer adsorption.The adsorption mechanisms consisted of electrostatic interaction,oxidation and inner sphere surface complexation. 相似文献
42.
43.
Yanke Yu Jiali Zhang Changwei Chen Chi He Jifa Miao Huirong Li Jinsheng Chen 《环境科学学报(英文版)》2020,32(5):237-245
CuSO_4/TiO_2 catalysts with high catalytic activity and excellent resistant to SO_2 and H_2 O,were thought to be promising catalysts used in Selective catalytic reduction of nitrogen oxides by NH_3.The performance of catalysts is largely affected by calcination temperature.Here,effects of calcination temperature on physicochemical property and catalytic activity of CuSO_4/TiO_2 catalysts were investigated in depth.Catalyst samples calcined at different temperatures were prepared first and then physicochemical properties of the catalyst were characterized by N2 adsorption-desorption,X-ray diffraction,thermogravimetric analysis,Raman spectra,Fourier-transform infrared spectroscopy,X-ray photoelectron spectroscopy,temperature-pro grammed desorption of NH_3,temperature-programmed reduction of H_2 and in situ diffuse reflectance infrared Fourier transform spectroscopy.Results revealed that high calcination temperature had three main effects on the catalyst.First,sintering and anatase transform into rutile with increase of calcination temperature,causing a decrement of specific surface area.Second,decomposition of CuSO_4 under higher calcination temperature,resulting in disappears of Br(?)nsted acid sites(S-OH),which had an adverse effect on surface acidity.Third,CuO from the decomposition of CuSO_4 changed surface reducibility of the catalyst and favored the process of NH_3 oxidation to nitrogen oxides(NO_x).Thus,catalytic activity of the catalyst calcined under high temperatures(≥600℃) decreased largely. 相似文献
44.
From 2000 to 2010 China experienced rapid economic development and urbanization. Many cities in economically developed areas have developed from a single-center status to polycentricity. In this study, we used exploratory spatial data analysis (ESDA) to identify the population centers, which identified 232 cities in China as having urban centers. COMP was used to represent urban agglomeration, and POLYD (representing how far is the city's sub-centers to the main center), POLYC (representing the number of a city's centers), and POLYP (representing the population distributed between the main center and the sub-centers) were used to indicate urban polycentricity. Night light data were used to determine the CO2 emissions from various cities in China. A mixed model was used to study the impact of urban aggregation and polycentric data on the CO2 emission efficiency in 2000 and 2010. The study found that cities with higher compactness were distributed in coastal areas, and the cities with higher multicentricity were distributed in the Yangtze River Delta and Shandong Province. The more compact the city was, the less conducive it was to improving CO2 emission efficiency. Polycentric development of the city was conducive to improving the CO2 emission efficiency, but the number of urban centers had no significant relationship with the CO2 emission efficiency. Our research showed that the compactness and multicentricity of the city had an impact on the CO2 emission efficiency and provided some planning suggestions for the low carbon development of the city. 相似文献
45.
Ozone pollution characteristics and sensitivity analysis using an observation-based model in Nanjing, Yangtze River Delta Region of China 总被引:1,自引:0,他引:1
Ming Wang Wentai Chen Lin Zhang Wei Qin Yong Zhang Xiangzhi Zhang Xin Xie 《环境科学学报(英文版)》2020,32(7):13-22
Ground-level ozone (O3) has become a critical pollutant impeding air quality improvement in Yangtze River Delta region of China. In this study, we present O3 pollution characteristics based on one-year online measurements during 2016 at an urban site in Nanjing, Jiangsu Province. Then, the sensitivity of O3 to its precursors during 2 O3 pollution episodes in August was analyzed using a box model based on observation (OBM). The relative incremental reactivity (RIR) of hydrocarbons was larger than other precursors, suggesting that hydrocarbons played the dominant role in O3 formation. The RIR values for NOX ranged from –0.41%/% to 0.19%/%. The O3 sensitivity was also analyzed based on relationship of simulated O3 production rates with reductions of VOC and NOX derived from scenario analyses. Simulation results illustrate that O3 formation was between VOCs-limited and transition regime. Xylenes and light alkenes were found to be key species in O3 formation according to RIR values, and their sources were determined using the Positive Matrix Factorization (PMF) model. Paints and solvent use was the largest contributor to xylenes (54%), while petrochemical industry was the most important source to propene (82%). Discussions on VOCs and NOX reduction schemes suggest that the 5% O3 control goal can be achieved by reducing VOCs by 20%. To obtain 10% O3 control goal, VOCs need to be reduced by 30% with VOCs/NOX larger than 3:1. 相似文献
46.
Dong Cao Ziyu Rao Fanglan Geng Hongyun Niu Yali Shi Yaqi Cai Yuehui Kang 《环境科学学报(英文版)》2020,32(11):67-74
Molecular level characterization of dissolved organic sulfur (DOS) by electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR MS) is necessary for further understanding of the role of DOS in the environment. Here, ESI spray solvent, a key parameter for ion production during ESI process, was investigated for its effect on the molecular characterization of DOS by ESI-FTICR MS. 100% MeOH as spray solvent was found for the first time to remarkably enhance the ionization efficiency of the majority of CHOS-molecules in NOM, which facilitated a total of 1473 CHOS-molecular formulas with one sulfur atom to be detected. The number of CHOS-molecular formulas obtained using 100%MeOH as spray solvent increased notably over 740 in comparison with those using 50% MeOH aqueous solution (731) or 50% ACN aqueous solution (653). Moreover, due to the enhancement of ionization efficiency of DOS during ESI processes, the tandem mass spectra of the NOM CHOS-molecules could be easily obtained using 100% MeOH as spray solvent, which were hardly obtained using 50% MeOH aqueous solution as spray solvent. The results of the tandem mass spectra suggested the first discovery of organosulfates or sulfonic acids in Suwannee River NOM sample. A simple method based on 100% MeOH as ESI spray solvent for advanced molecular characterization of DOS by ESI-FTICR MS was proposed and applied, and the results revealed more molecular information of DOS in sea DOM samples. 相似文献
47.
Hao Yu Xueyan Zhao Jing Wang Baohui Yin Chunmei Geng Xinhua Wang Chao Gu Lihua Huang Wen Yang Zhipeng Bai 《环境科学学报(英文版)》2020,32(9):217-224
In order to understand the compositions characteristics of particulate matter with aerodynamic diameter less than 2.5 μm (PM2.5) fraction in road dust (RD2.5) of oasis cities on the edge of Tarim Basin, 30 road dust (RD) samples were collected in Kashi, Cele, and Yutian in the spring, 2018, and RD2.5 was collected using the resuspension approach. Eight water-soluble ions, 39 trace elements and 8 fractions of carbon-containing species in PM2.5 were analyzed. Ca2+ and Ca were the most abundant ions and elements in RD2.5 (7.1% and 9.5%). Cl- in RD2.5 was affected not only by attributed to saline-alkali soils in oasis cities of the Tarim Basin and dust from Taklimakan Desert but also by human activities. Moreover, the organic carbon/elemental carbon (OC/EC) ratio indicated that carbon components in RD2.5 in Cele town mainly come from fossil fuel combustion, while those in Yutian and Kashi mainly come from biomass combustion. It is noteworthy that high Ca in RD2.5 was seriously affected by anthropogenic emissions, and high Na and K contents in RD2.5 could be derived from soil and desert dust. It was estimated that Cd, Tl, Sn and Cr were emitted from anthropogenic emissions using the enrichment factor. The coefficients of divergence (COD) result indicated that the influence of local emission on road dust emission is greater than that of long-distance transmission. This study is the first time to comprehensively analyze the chemical characteristics of road dust in oasis cities, and the results provides the sources of road dust at the margin of Tarim Basin. 相似文献
48.
In order to reduce the pollutant emission and alleviate the pressure of petroleum resources shortage and greenhouse gas emission at the same time, the use of clean and renewable alternative fuel for marine engines is a promising option. In this study, a marine diesel engine, which was modified to run in diesel methanol compound combustion (DMCC) mode, was investigated. After the diesel injection parameters were calibrated, and combined with a sample after-treatment device DOC (diesel oxidation catalyst), the engine could meet the requirements of China II legislation. The overall MSP (methanol substitute percent) reached 54.1%. The value of each pollutant emission was much lower than that in China II emission legislation, and there was almost no methanol and formaldehyde emissions. When methanol was injected into the inlet manifold, the intake air temperature decreased a lot, as well as the exhaust gas temperature, which were beneficial to increase engine thermal efficiency and improve engine room environment. Compared with the engine running in pure diesel mode, when the engine ran in diesel/methanol dual fuel mode, the combustion phase was advanced, and the combustion duration became shorter. Therefore, the engine thermal efficiency increased, and fuel consumption decreased significantly. 相似文献
49.
As a novel alternative to traditional perfluoroalkyl substances (PFASs), including perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), hexafluoroproplyene oxide trimer acid (HFPO-TA) has been detected worldwide in surface water. Moreover, recent researches have demonstrated that HFPO-TA has stronger bioaccumulation potential and higher hepatotoxicity than PFOA. To treat these contaminants e.g. PFOA and PFOS, some photochemical techniques by adding exogenous substances had been reported. However, there is still no report for the behavior of HFPO-TA itself under direct UV irradiation. The current study investigated the photo-transformation of HFPO-TA under UV irradiation in aqueous solution. After 72 hr photoreaction, 75% degradation ratio and 25% defluorination ratio were achieved under ambient condition. Reducing active species, i.e., hydrated electrons and active hydrogen atoms, generated from water splitting played dominant roles in degradation of HFPO-TA, which was confirmed by different effects of reaction atmospheres and quenching experiments. A possible degradation pathway was proposed based on the products identification and theoretical calculations. In general, HFPO-TA would be transformed into shorter-chain PFASs, including hexafluoropropylene oxide dimer acid (HFPO-DA), perfluoropropionic acid (PFA) and trifluoroacetate (TFA). This research provides basic information for HFPO-TA photodegradation process and is essential to develop novel remediation techniques for HFPO-TA and other alternatives with similar structures. 相似文献
50.
为了促进污水处理厂剩余污泥的资源化利用,探索S-HA(sludge-based humic acid, 污泥腐殖酸)对溶液中重金属Cd2+的吸附特性.采用国际腐殖酸协会(IHSS)推荐的方法提取S-HA,通过元素分析、FT-IR(傅里叶红外光谱分析)和SEM-EDS(外观形态分析)等方法,考察溶液pH和共存阳离子对吸附过程的影响,并对吸附过程分别进行了吸附动力学模型、等温吸附模型和吸附热力学模型拟合,同时通过对比S-HA吸附前后的红外光谱和扫描电镜-能谱图片,探索S-HA对Cd2+的吸附机制.结果表明:①S-HA表面呈松散的簇团状,含有大量的羧基、醇羟基和酚羟基等含氧官能团,芳香度较高,含有较多的脂肪链结构;S-HA在吸附水中Cd2+的过程中,Cd2+与S-HA表面上的酚羟基、羧基等官能团发生了络合作用.②S-HA对Cd2+的吸附量随溶液pH升高而增加,溶液中Na+、NH4+和Ca2+等共存阳离子的存在不利于S-HA对Cd2+的吸附,其中Ca2+的存在对S-HA吸附Cd2+影响最大.③S-HA对Cd2+的吸附由快吸附、慢吸附和吸附平衡3个阶段组成,吸附平衡时间为12 h;吸附过程符合准二级动力学模型,其整体吸附速度由液膜扩散和颗粒内扩散共同控制;吸附等温线符合Freundlich等温吸附模型,25℃下的最大吸附量为19.29 mg/g,Cd2+在S-HA上的吸附是自发吸热反应.研究显示:污水处理厂剩余污泥提取的S-HA对Cd2+具有较好的吸附效果;S-HA对Cd2+的吸附过程同时存在着物理吸附和化学吸附;高pH对S-HA吸附Cd2+有促进作用,而高离子强度对S-HA吸附Cd2+有抑制作用. 相似文献